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Hip and Knee Replacement
June 8, 2015
We have come along way in the knowledge of how to replace worn out joints due to disease, trauma, or congenital deformities. The most common joints replaced are the hip and knee. The first hip replacement was done by a British surgeon, Sir John Charnley, about 40 years ago. He didn't even wear gloves during the procedure I have been told! The first knee was replaced in 1968. Each year about 150,000 knees are replaced in the United State, alone.
Why do we replace these joints, and what should we expect? More than likely, you know someone who has had a hip or knee replaced. Statistically, 90% of those people are pleased with the results. That's not too bad, when you understand more fully what is being done and the pitfalls that could happen.
The ends of our bones in the joints are covered with a substance called articular cartilage. Next time you eat a chicken leg, look at the rounded ends of the bone. Now you know what it is. This cushions the bone where they meet, and allow for an easy gliding movement. A lubricant, like motor oil, is released in the joint, to "grease" the parts so the friction is minimized. Normally, this whole system works great, and we walk through most of our lives with no problems.
However, let's throw some wrenches in the machine. The most common cause of hip and knee pain is arthritis, (or "arther-itus" as many folks call it). The more obvious types of arthritis are osteoarthritis, rheumatoid, and traumatic. Osteoarthritis usually occurs after the age of 50, and often seen in people with a family history of it. The cartilage just wears out and bones start grinding against each other. Ouch, that's gotta hurt! Rheumatoid arthritis is a disease where the lining of the joint becomes chronically inflamed, and eventually destroys the cartilage. Traumatic arthritis is exactly what it sounds like: it usually follows a serious injury to the joint causing the joint to wear out prematurely.
When does one decide if they should have their hip or knee replaced? Usually when the pain is crippling due to all activity, even at night, and it interferes with one's daily activities and work. These are major surgical procedures, and a good support group with the family, spouse, and physical therapists are necessary to maximize the best possible outcome. Often, these patients have tried all the nonsurgical avenues, and nothing can relieve the pain. Many people will come to their physician long before they need to have a joint replaced, as the pain is gradually worsening. As we have no cure for arthritis, understanding what we can do to get the most miles out of our joints enables us to avoid surgery longer.
Arthritis is a disease that stiffens and can dry up the joint, kind of like a rusty hinge, the joint just doesn't move too freely and grinds when it does. One form of treatment for arthritic knees is serial injections of an artificial knee lubricant: like oil to the rusty hinge, this can free up the joint, act as a lubricant and decrease the pain. Regular exercise in a low impact environment, like aerobic swimming exercises or a stationary bicycle can do wonders to get the joint lubricated and moving again. Unfortunately, living in an extreme cold weather environment like Fairbanks often will exacerbate the symptoms, and make the pain worse. There is a reason why Arizona and Florida are big retirement states. Retiring folks don't move there to work on their tans, but rather it is the warm weather that makes their arthritis feel better!
When a hip or knee is replaced, all the parts are usually replaced with metal or plastic components. Usually, a specially designed bone cement is used to glue these parts firmly in place. The cement is mixed in the operating room, and in about 15 minutes it is hard as granite. As I had a tooth capped last spring, I thought about the similarities of that crown and the parts of joints when they are replaced. As I said, about 90% of all people are pleased with the outcome of having their hip or knee replaced. The joint is never as good as the one that was there when there was no pain, but it sure is a better alternative than being crippled all the time.
Activities must be limited after a joint is replaced, as extreme physical activity like jogging, contact sports, or high impact aerobics could lead to early loosening of the components. Acceptable activities include light hiking, swimming, golf, recreational walking and biking, and simple dancing. Skiing and tennis are usually not recommended, as is lifting objects over 50 lbs. repeatedly.
Most people stay in the hospital from 4-7 days, are then sent to a rehabilitation center or home under the care of daily physical therapy visits. Physical therapists play such an important role in getting the best possible outcome, as they can encourage and motivate during those weeks of rehab following surgery. It usually takes about 3-6 months to fully recover, and during that time progression is documented regularly.
Joint replacement surgery is not for everyone, as certain restrictions do apply. Most people who qualify are in their 6th or 7th decade of life, and have no major health problems. Long term failure can be attributed to loosening of the parts, wear, or infection. 75% of all failures of joint replacement are due to the parts simply wearing out. Just like our shoes, they wear out after years of walking on them. So goes the artificial joints. Fortunately, revision surgery can be offered under the right circumstances. This is why we try not to replace joints in younger individuals, especially men. They tend to wear them out sooner, all that moose hunting I guess. Less active folks have higher success rates than younger active individuals.
Arthritis can be a painful and frustrating problem. Some studies show that glucosamine and chondroitin sulfate can help ease the pain, and many people take it successfully. I have had patients tell me WD-40 rubbed on the joint helps! I wouldn't recommend that, but with proper education and counseling, the problems of arthritis can often be improved to avoid surgery